The blades of Moore & Wright 400 series BS939 Grade B 6" Engineers' squares are straight to a maximum total deviation of 8 microns, the working faces of the stock are ground to a unilateral (concave) tolerance of 6 microns and the two are square to each other (inside and outside) to a maximum total deviation of 16 microns.
Engineers squares have largely replaced conventional woodworking squares because of their superior ability to remain square.
A square is a tool for transferring squareness. They should be regularly checked against an inspection square (that is never used for anything else) and adjusted if necessary by judicious tapping of the corners against a soft but sturdy surface.
These Moore & Wright 400 series Engineers' squares are very accurately manufactured bits of kit indeed. I took a random selection of 15 of them in various sizes and systematically compared the inside and outside of each one with the outside and inside of every other one - spot on throughout!
- 150mm / 6" (internal dimension)
- BS939 Grade B
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After failed attempts at buying cheaper traditional carpenters squares, I bit the bullet and got this. Why didn't I just buy it in the first place?! I'm now starting off on the right foot at the marking stage - and checking too. I highly recommend this, at a great price for the excellent quality.
None of my squares are the same.I now know what to trust and what to true up. I've never been so pleased to buy something that will stay in its oiled paper safely in the drawer.
I have just reviewed the 2 smaller squares so I really am repeating myself now. We recommend these squares to all our students here at Waters and Acland Furniture School and Workshop. They are excellent and square!!!
Beautifully engineered and a pleasure to use and up to Moore and Wright usual standards. Definitely worth the money.
This is a great square, but as always it is not always the perfect tool. Now you (or I) want a smaller one when this one won't do!
Moore & Wright, one of the most highly respected firms from Sheffield, should and do deliver what's expected in measurement.